IBM ThinkCentre 8105 Hardware Replacement Manual page 19

a. Take notice of the orientation of the notches 1 on the microprocessor.
This is important when installing the microprocessor on the new system
board.
b. Do not drop anything on the socket while it is open. Keep all contacts as
clean as possible.
14. On the new system board, release the lever securing the microprocessor
retainer then pivot the retainer until it is fully open.
15. Position the microprocessor so that the notches on the microprocessor are
aligned with the tabs in the microprocessor socket.
Important
To avoid damaging the microprocessor contacts, do not tilt the
microprocessor when installing it into the socket.
16. Use the vacuum pen 1 to lower the microprocessor straight down into the
system board socket of the new system board.
Chapter 2. Replacing hardware
11